I recently tried XBMC again, after having tried and given up a few years ago. (I believe I first used it at XBMC-9.x, and when it upgraded to XBMC-10.x I had build problems, and gave up.) In XBMC-9.x I found the MythTV plugin to be "too flat" when displaying my recorded video.

In XBMC-12 I "somehow" found and installed the MythTV plugin, but then saw that it was for mythtv-0.25.0 when I was (and still am) running mythtv-0.25.3, and indeed it didn't talk to my server. I don't remember if I've gotten around to removing XBMC or not, yet. Nor do I remember exactly how I installed the plugin, just that it wasn't going to work for me because of the vintage mismatch._________________.sigs waste space and bandwidth

Yes, it seems to be quite a mess with the different versions of xbmc and MythTV. So I had to accept that MythBox addon in xbmc does not cope with MythTV 0.26. Got that after inserting the credentials for the MythTV server for about 20 times! Also the other possible ways to connect xbmc to MythTV are either too old or not supporting the current version. It's kind of a puzzle with moving targets.

I didn't want to mention it first, but I installed xbmc on my notebook. My wife also uses this notebook and "forbid" me to install Linux, so it runs on MS Windows (unfortunately). Installation was three clicks and all plugins were where they ought to be. Connecting to my MythTV server was a piece of a cake, hmmm ...

After switching from pure alsa to pulseaudio Mythfrontend is working again.

Still I do not find the pvr plugin for MythTV in xbmc. I emerged xbmc for several times now including the explicit use of USE="pvr" although I have it written in /etc/portage/package.use already.
I really wonder where this plugin went?